To-do Lists 1.x : No syncing anymore

Unfortunately Dropbox shut down v1 of their API : https://blogs.dropbox.com/developers/2016/06/api-v1-deprecated/
Since To-do Lists 1.x app was developed years ago and aimed to support old OS versions most likely we will not spend time on updating it.
Instead we’ll continue work on To-do Lists 2.0, which will include Dropbox/iCloud syncing support as well.
Sorry for inconvenience.